London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

Artist Peter Fischli today insisted there was no risk to passers-by from this sculpture — even though there is nothing fixing the boulders together.

Fischli, from Switzerland, compared making the piece to the childhood habit of piling up objects. But he said engineers Arup had worked with him to ensure that the work, for the Serpentine Gallery, was entirely stable.

“Especially from certain angles, it has this moment of doubts,” he said. “It’s kind of faking something that nature might have done. But the English park, where it sits, also has this idea of faking nature about it. It fits the park perfectly.”

Rock on Top of Another Rock will be in Kensington Gardens for 12 months. It was conceived by Fischli with his long-term collaborator David Weiss, inspired by a previous commission in a boulder field in Norway. They had sourced the glacial rock from Wales when Weiss died of cancer aged 65 last April.

Fischli, 60, said his death was a “sad moment” but everyone involved in the project thought it should go ahead. “Seeing it, I am really super happy.”